Design and synthesis of new bis-hydrazones and pyridine bis-hydrazones: Application in the asymmetric Diels-Alder reaction

Abstract

The design of two different types of new chiral bis-hydrazones 5 (bidentate N,N ligands, type A) and pyridine bis-hydrazones 7 ('pincer' N,N,N ligands, type B) is discussed. Preliminary results on the copper(II)-catalyzed Diels-Alder reaction of N-(E)-crotyloxazolidin-2-one (8) with cyclopentadiene (9) revealed that the (2S,6S)-2,6-diphenylpiperidine C2-symmetric substructure in pyridine bis-hydrazone ligand 7c is the key design element leading to good enantioselectivities. ©ARKAT-USA, Inc.